1. Field of the Invention
The invention relates to a bubble level assembly, such as the type used by a carpenter.
2. Description of the Related Art
A typical carpenter's level is an elongate generally rectangular structure having opposite first and second ends. Planar top and bottom faces are aligned parallel to one another and extend between the ends. The top and bottom faces are the portions of the prior art level that are placed against another surface for assessing horizontal or vertical alignment of the surface. The prior art level also has a front face and a rear face that connect the top and bottom faces and the respective ends. The front and rear faces on most prior art levels are parallel to one another. However, the prior art also includes torpedo levels that have the front and rear faces tapering towards one another in proximity to the respective ends of the level. Many other prior art levels have recessed front and rear faces so that the level has a cross section that resembles an I-beam.
A typical prior art level includes a plurality of glass tubes that are filled partly with a liquid spirit. The portion of the tube that is not filled by the liquid forms a bubble. Movement of the level will cause the liquid to shift gravitationally within the tube, and hence will cause a repositioning of the bubble. The tube includes a pair of lines that are spaced apart by a distance approximately equal to the length of the bubble. The liquid will be disposed symmetrically relative to the lines on the tube when the tube is aligned horizontally. As a result, the bubble will be positioned precisely between the lines. The typical prior art level includes at least a first tube aligned parallel to the top and bottom faces of the level and at least a second tube aligned perpendicular to the top and bottom faces of the level. Some prior art levels are configured to permit one or more of the bubble tubes to be rotated in the level between a position where the tube is parallel to the top and bottom faces, a position where the tube is perpendicular to the top and bottom faces and possibly one or more intermediate positions.
A good quality short level often is adequate for assessing the horizontal or vertical alignment of a generally planar surface. A short level also can be easier to manipulate than longer levels. However, levels can be used to assess the alignment of the high points on an uneven surface. A short level may not have sufficient length to rest properly on two spaced-apart high points on an even surface. Levels also are used frequently to compare the alignment of two spaced apart objects, such as beams in a building. For example, a carpenter may want to install gypsum board across studs of a wall or ceiling or a carpenter may want to secure plywood or particle board to floor beams. Beams are not always level with one another, even on new construction. Beams on older structures rarely are level. As a result, the carpenter may want to assess the levelness across several beams. The carpenter may then use lath or other thin strips of wood to shim up the lower beams. Alternatively, a carpenter may chose to add a nailing strip to the side of a lower beam to bring the lower beam up to level with the higher beams.
Line levels can be used to assess the degree of levelness across several beams. The line level typically is very small and has clips to permit mounting on a string. The combination of the line level and the string enable an assessment of levelness across a considerable distance. However, strings are affected by gravity and will sag due to the weight of the string and the weight of the level. As a result, line levels generally do no provide very high precision. Furthermore, the positioning of a line level is complex and time consuming.
Laser levels permit accurate assessment of levelness across a considerable distance. However, a good quality laser level is fairly expensive and can be complicated to set up, calibrate and use.
A good quality carpenter's level generally can be purchased for a reasonably cost and can be used quickly without a complicated set up or calibration. However, the many possible uses for a carpenter's level have required carpenters and many homeowners to maintain a collection of levels of different dimensions. Most carpenters will carry a short torpedo level that may be less than one foot long. The typical carpenter also will carry a level of 24 or 36 inches and a level of 48 inches. A 24 or 36 inch level typically is long enough to span two or three beams. The 48 inch level is long enough to span the width of a four foot by eight foot sheet gypsum board or plywood and the beams to which such a sheet will be secured. Carpenters also must carry many other tools. Hence, the need for several levels of different dimensions complicates the tool inventory management responsibilities of a carpenter. In particular, the carpenter must be certain that all required tools are carried to the job and are removed from the job. The need for three or more levels complicates this effort.
The prior art includes multi-component levels that can be assembled and disassembled to accommodate the needs of a particular job. The typical prior art multi-component level includes a plurality of level segments that can be attached in end-to-end relationship. Levels or this type are shown, for example, in U.S. Pat. Nos. 1,132,318, 1,605,604 , 2,383,166, 5,433,011 and Published U.S. Pat. No. 2002/0121025. Good quality end-to-end connections can be costly to manufacture. Furthermore, the various segments of such a level are difficult to align properly in end-to-end relationship to effect the connection, and the various level segments can disconnect unintentionally if not connected properly. Furthermore, levels often are used in environments near dirt or other debris. Such debris can soil the ends of the level segments that must be connected, and hence can further complicate assembly and disassembly. The small interconnectable parts at the end of such a level are not easily cleaned.
The subject invention has been made in view of the above described problems. Accordingly, it is an object of the invention to provide a level assembly that can accommodate the various space requirements and limitations for the work environment in which the level is used.
It is a further object of the invention to provide a level that can be transported easily to and from a job.
Another object of the invention is to provide a level assembly that can be assembled and disassembled very easily.
It is another object of the subject invention is to provide a level assembly that can be cleaned and maintained easily.